National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China.
Acta Biochim Biophys Sin (Shanghai). 2020 Apr 20;52(4):446-456. doi: 10.1093/abbs/gmaa011.
Self-incompatibility (SI) promotes outbreeding and prevents self-fertilization to promote genetic diversity in angiosperms. Several studies have been carried to investigate SI signaling in plants; however, protein phosphorylation and dephosphorylation in the fine-tuning of the SI response remain insufficiently understood. Here, we performed a phosphoproteomic analysis to identify the phosphoproteins in the stigma of self-compatible 'Westar' and self-incompatible 'W-3' Brassica napus lines. A total of 4109 phosphopeptides representing 1978 unique protein groups were identified. Moreover, 405 and 248 phosphoproteins were significantly changed in response to SI and self-compatibility, respectively. Casein kinase II (CK II) phosphorylation motifs were enriched in self-incompatible response and identified 127 times in 827 dominant SI phosphorylation residues. Functional annotation of the identified phosphoproteins revealed the major roles of these phosphoproteins in plant-pathogen interactions, cell wall modification, mRNA surveillance, RNA degradation, and plant hormone signal transduction. In particular, levels of homolog proteins ABF3, BKI1, BZR2/BSE1, and EIN2 were significantly increased in pistils pollinated with incompatible pollens. Abscisic acid and ethephon treatment partially inhibited seed set, while brassinolide promoted pollen germination and tube growth in SI response. Collectively, our results provided an overview of protein phosphorylation during compatible/incompatible pollination, which may be a potential component of B. napus SI responses.
自交不亲和性 (SI) 促进异交，防止自花授粉，从而促进被子植物的遗传多样性。已经有几项研究致力于研究植物中的 SI 信号转导；然而，蛋白质磷酸化和去磷酸化在 SI 反应的微调中仍然理解不足。在这里，我们进行了磷酸蛋白质组学分析，以鉴定自交亲和的“西塔”和自交不亲和的“W-3”甘蓝型油菜品系柱头中的磷酸蛋白。总共鉴定出 4109 个磷酸肽，代表 1978 个独特的蛋白质组。此外，分别有 405 和 248 个磷酸蛋白对 SI 和自交亲和反应有显著变化。酪蛋白激酶 II (CK II) 磷酸化基序在自交不亲和反应中富集，并在 827 个主要 SI 磷酸化残基中鉴定出 127 次。鉴定出的磷酸蛋白质的功能注释表明这些磷酸蛋白质在植物-病原体相互作用、细胞壁修饰、mRNA 监测、RNA 降解和植物激素信号转导中发挥主要作用。特别是，授粉后雌蕊中同源蛋白 ABF3、BKI1、BZR2/BSE1 和 EIN2 的水平显著增加。脱落酸和乙烯处理部分抑制结实，而油菜素内酯促进 SI 反应中的花粉萌发和管生长。总的来说，我们的结果提供了在亲和/不亲和授粉过程中蛋白质磷酸化的概述，这可能是油菜 SI 反应的一个潜在组成部分。
